How do you change MongoDB user permissions?

Question

For instance, if I have this user:

> db.system.users.find()
{ \"user\" : \"testAdmin\", \"pwd\" : \"[some hash]\", \"roles\" : [ \"clusterAdmin\" ], \"otherDB         


        

Answer 1

See array update operators.

> db.users.findOne()
{
    "_id" : ObjectId("51e3e2e16a847147f7ccdf7d"),
    "user" : "testAdmin",
    "pwd" : "[some hash]",
    "roles" : [
        "clusterAdmin"
    ],
    "otherDBRoles" : {
        "TestDB" : [
            "readWrite"
        ]
    }
}
> db.users.update({"user" : "testAdmin"}, {$addToSet: {'otherDBRoles.TestDB': 'dbAdmin'}}, false, false)
> db.users.findOne()
{
    "_id" : ObjectId("51e3e2e16a847147f7ccdf7d"),
    "user" : "testAdmin"
    "pwd" : "[some hash]",
    "roles" : [
        "clusterAdmin"
    ],
    "otherDBRoles" : {
        "TestDB" : [
            "readWrite",
            "dbAdmin"
        ]
    },
}

Update:

MongoDB checks permission on every access. If you see operator db.changeUserPassword:

> db.changeUserPassword
function (username, password) {
    var hashedPassword = _hashPassword(username, password);
    db.system.users.update({user : username, userSource : null}, {$set : {pwd : hashedPassword}});
    var err = db.getLastError();
    if (err) {
        throw "Changing password failed: " + err;
    }
}

You will see — operator changes user's document.

See also system.users Privilege Documents and Delegated Credentials for MongoDB Authentication